Friday, Jan. 11, 2013

Have a safe day!

Friday, Jan. 11

3:30 p.m.

4 p.m.
Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Rolf Ent, Thomas Jefferson National Accelerator Laboratory
Title: Probing the Quark Sea and Gluons: The Electron-Ion Collider Project

Monday, Jan. 14


3:30 p.m.


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Wilson Hall Cafe

Friday, Jan. 11

- Breakfast: French bistro basket
- New England clam chowder
- Becks battered fish sandwich
- Tortellini alfredo
- Smart cuisine: Herb and lemon fish
- Cuban panini
- Assorted pizza by the slice
- Szechuan green beans with chicken

Wilson Hall Cafe Menu
Chez Leon

Friday, Jan. 11
Guest chefs: Grace and Gary Leonard
- Pear, blue cheese and walnut salad
- Cocoa crusted pork tenderloin
- Potato cakes
- Haricots verts
- Blueberry upside-down cake with cream chantilly

Wednesday, Jan. 16
- Balsamic glazed salmon
- Roasted new potatoes
- Brussels sprouts
- Lemon cheesecake

Chez Leon Menu
Call x3524 to make your reservation.


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From symmetry

Midwest muon experiments carry on East Coast legacy

The Muon Campus at Fermilab would be the home of the proposed Muon g-2 and Mu2e experiments. symmetry writer Joseph Piergrossi sat down with collaborators from Boston University to learn more about the projects' goals and history. Image: Muon Department/FESS

This spring, scientists at Fermi National Accelerator Laboratory will break ground on the buildings for a Muon Campus. The two initial experiments proposed for the campus draw on three decades of technological advances to turn muons into supersensitive probes for physics beyond the Standard Model.

With the planned Muon g-2 experiment, scientists aim to discover signs of subatomic particles and forces that have eluded detection by other experiments. It will be more sensitive to virtual or hidden particles and forces than any previous experiment of its kind. The Mu2e experiment will test a fundamental symmetry of the quantum world. Scientists have observed the transformation of one type of quark into another, as well as the transition of one type of neutrino into another. The question remains: Can the muon, a charged lepton, change into another type of charged lepton? In particular, can a muon turn into an electron?

Muon g-2 (pronounced g minus two), the first experiment to be installed in the new Muon Campus at Fermilab, has its roots in a muon experiment of the same name that ran from 1997 to 2001 at Brookhaven National Laboratory. The experiment's goal is to measure with high precision the magnetic dipole moment of the muon. The quantity g specifies exactly how much a muon wobbles—or precesses—in a magnetic field.

"The muon is very sensitive to the hidden presence of new physics," says Lee Roberts, professor of physics at Boston University and co-spokesperson for the Muon g-2 experiment.

The Brookhaven Muon g-2 experiment had its inception in 1982, when Yale physicist Vernon Hughes suggested an experiment to measure the magnetic dipole moment of the muon 20 times better than previous experiments run at CERN in the 1970s. He and Roberts were the co-spokespeople for the Brookhaven project and headed the design of the experiment, which eventually involved scientists from 14 institutions in five countries. It required firing muons into a 50-foot-diameter muon storage ring that produced an exceptionally uniform magnetic field. Muons circled the ring many times before decaying. Particle detectors recorded the decays to discern the nature of the muons' precession.

Boston University has had a major stake in the Muon g-2 experiments at Brookhaven and now at Fermilab. In the early 1990s, the university provided the facilities to construct many important components of the muon ring. It was one of a half dozen institutions that "played a crucial role" in the experiment, says Brookhaven's Bill Morse, former resident spokesperson for the Muon g-2 project.

Brookhaven's Muon g-2 experiment produced the best measurement of the wobble, g, to date, and the result doesn't agree with the predictions stemming from the theoretical framework known as the Standard Model of particles and forces. In the absence of quantum effects, g should equal 2. Taking into account all the known particles and forces, theorists can calculate with high precision how much g should differ from 2, which led to the experiment's name. The Brookhaven experiment, however, produced a cliffhanger. It measured g-2 to be outside the Standard Model's predictions with a confidence level of three sigma, meaning that there is a less than 1 in 370 chance that the experiment would observe a deviation of this magnitude from the Standard Model's prediction. For scientists, that is not enough to claim the discovery of a discrepancy, but enough to produce sleepless nights.

After the conclusion of the experiment at Brookhaven, Roberts and other collaborators, including David Hertzog of the University of Washington (the other co-spokesperson of Muon g-2), were looking for a place to make a more precise measurement.

"Hertzog and I explored all around the world, and we concluded the best place was Fermilab," Roberts says. Fermilab's accelerators will enable the new experiment to collect data on more than 20 times the number of muons, an intensity that should lead to a more precise measurement of g-2 and a five-sigma discovery, if the initial observation was not a statistical fluctuation.

The Muon g-2 scientists hope to start recording data at Fermilab in less than three years. Theorists already have some ideas as to why g-2 might not agree with the Standard Model prediction. A theory known as supersymmetry predicts the existence of extra particles and forces, which modify the g-2 calculations.

"Supersymmetry predicts the Muon g-2 results we have so far," says Brookhaven's Morse. "It also predicts that the muon converts into an electron."

Read more

Joseph Piergrossi

In the News

The farthest supernova yet for measuring cosmic history

From Berkeley Lab News Center, Jan. 9, 2013

What if you had a "Wayback Television Set" and could watch an entire month of ancient prehistory unfold before your eyes in real time? David Rubin of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) presented just such a scenario to the American Astronomical Society (AAS) meeting in Long Beach, CA, when he announced the discovery of a striking astronomical object: a Type Ia supernova with a redshift of 1.71 that dates back 10 billion years in time. Labeled SN SCP-0401, the supernova is exceptional for its detailed spectrum and precision color measurement, unprecedented in a supernova so distant.

Read more
In the News

Supernova 'Mingus' could shed light on dark energy

From BBC News, Jan. 10, 2013

Astronomers have spotted the most distant supernova ever seen.

Nicknamed "Mingus", it was described at the 221st American Astronomical Society meeting in the US.

These lightshows of dying stars have been seen since ancient times, but modern astronomers use details of their light to probe the Universe's secrets.

Ten billion light-years distant, Mingus will help shed light on so-called dark energy, the force that appears to be speeding up cosmic expansion.

Read more
Frontier Science Result: CMS

Editor's note: Starting this year, Fermilab Today will bring you more results from research at the Energy, Intensity and Cosmic Frontiers. We will publish these results on Thursdays and Fridays, highlighting the full breadth of Fermilab's experiments.

Is it the Higgs boson?

Particles have intrinsic spin and parity. Parity depends on what happens if you swap left for right, up for down and forward for backward. Positive parity means you won't see a difference, while negative parity means you'll see the opposite. The Higgs boson is predicted to have zero spin and positive parity. This analysis establishes the particle found in July 2012 most likely has positive parity, at least in the decay channel into two Z bosons.

On July 4, 2012, the CMS and ATLAS experiments announced the discovery of a new particle with a mass of 125 GeV. This particle was widely heralded in the press as the Higgs boson, but both experiments very carefully didn't make that claim. Instead, both experiments used the language "a particle consistent with being a Higgs boson."

So why were the experiments so cagey in their announcement? It's very simple. The Higgs boson was predicted in 1964 to have very specific properties. It is a massive particle, neutral and containing no particles inside it. Getting a little more esoteric, the Higgs boson is also predicted to have zero quantum mechanical spin and positive parity. The latter has to do with what happens if you swap left with right, up with down and forward with backward.

So what do we know? Well, evidence suggested that the discovered boson decayed into pairs of fermions (bottom quarks and tau leptons, both with spin 1/2) and pairs of bosons (W and Z bosons and photons, with spin 1). From this simple observation, we can infer that the newly discovered particle was electrically neutral (a prediction of Higgs theory) and was a boson (another successful prediction). In addition, using what we know about the spin of the decay products and combining that with the rules of quantum mechanics, we also know from the particle's decay into bosons that the spin of the parent had to be 0 or 2.

A spin 0 particle would support the Higgs hypothesis, while a spin 2 particle, not being predicted, might be even more interesting. On the other hand, the universe might be malicious, and the July 2012 announcement could be referring to not only one, but maybe two particles, with spins of 0 or 2 and with masses close enough to each other that we thought we were seeing just one particle when we might actually have been seeing two. Further, a particle decaying into fermions could have a spin of 1.

Thus the only way to be sure is to directly measure things like the spin and parity of the newly discovered particle(s?). To do that, we have to exploit things like the angular decay patterns. Using the decay chain of the newly discovered particle into pairs of Z bosons (which decay, in turn, into electron or muon pairs), we can explore the spin and parity of the new particle. While the data is not yet strong enough to distinguish between a spin 0 or a spin 2 particle, we can set a strong limit on the parity. The analysis strongly favors a positive parity over a negative parity. Since the Higgs boson is predicted to have positive parity, we can add one more bit of evidence to the case that the new particle is the Higgs boson. In addition, the mass of the new boson was measured very accurately, with a precision of about 0.5 percent. It is very important to measure the mass with extreme precision to guard against the possibility that several particles with nearly identical masses have fooled us into thinking only one was found.

This is not the last tale in the saga of the discovery (and verification of the discovery) of the Higgs boson, but it's an important one. Others will be announced as they become available.

—Don Lincoln

These U.S. physicists contributed to this analysis.
These members of the Fermilab Electrical Engineering Department are working on the new front-end electronics that are critical for the CMS hadron calorimeter readout upgrade. These new electronics will provide both energy measurement and the time that the energy arrives at the chip. The timing information will help physicists sort out what is going on when 20 or more collisions occur simultaneously inside the CMS detector.

Today's New Announcements

Barn Dance - Jan. 13

NALWO Armenian cooking demonstration - Jan. 24

UChicago panel discussion on Higgs discovery - Feb. 7

Interpersonal Communication Skills course offered in May

Fermilab Lecture Series - Building Bionics - Jan. 18

Gallery Chamber Series - Metropolis Quartet - Jan. 20

Fermilab Arts Series - Tomas Kubinek - Jan. 26

January 2013 timecards and float holiday

Zumba offered Tuesdays and Fridays

2013 FRA scholarship applications accepted until April 1

Fermilab Management Practices courses available for registration

International Folk Dancing Thursday evenings in Kuhn Barn

Martial arts classes

Indoor soccer

USA Athletic Club and Spa discount for employees

Employee discounts on AAA membership

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